Spark plug adjusting tool

ABSTRACT

A spark plug adjusting tool for adjusting the spacing between the electrodes of a spark plug. The tool is threadedly secured to the threads of the spark plug and an adjusting screw or screws are provided for applying a force to the deformable electrode. One form of the invention is for use on automotive spark plugs where only one pair of electrodes are involved. Another form of the invention is for aircraft spark plugs in which one stationary central electrode is provided and a plurality of deformable electrodes are arranged around the central electrode.

United States Patent Sydow Aug. 12, 1975 [54] SPARK PLUG ADJUSTING TOOL 3,777,535 12/1973 Paxton 72/454 'h M. d ,836D"1D., [76] Inventor RIC ow dme r Przmary Exammer-C. W. Lanham Petaluma, Calif. 94952 Assistant Examiner-Gene P. Crosby [22} Filed: Nov. 23, 1973 211 Appl. No.: 418,246 1 ABSTRACT A spark plug adjusting tool for adjusting the spacing between the electrodes of a spark plug. The tool is 7 125, 72 454, 72 457 2/ /B2ld 2/6/02 threadedly secured to the threads of the spark plug [58] Fie'ld 454 457 and an adjusting screw or screws are provided for ap- 29/03 plying a force to the deformable electrode. One form of the invention is for use on automotive spark plugs [56] References Cited where only one pair of electrodes are involved. An-

ATENTS other form of the invention is for aircraft spark plugs UNITED STATES P in which one stationary central electrode is provided 1,985,410 112/1934 lsaacs 72/293 and a plurality of d f bl electrodes are arranged g h zf around the central electrode. c u 2,482.703 9/1949 Call 72/ 125 2 Claims, 4 Drawing Figures SPARK PLUG ADJUSTINGTOOL This invention relatesto a tool for adjusting the spacing between the electrodes of a spark plug. Heretofore the customary procedure in adjusting the spacing between the electrodes of a spark plug has been to check the clearance between the electrodes with a feeler gage and to pry the deformable electrode away from the fixed electrode with a screwdriver or like tool when the clearance is too small. It is then usually necessary to move the deformable electrode toward the fixed electrode until the desired clearance is achieved. This procedure not only involves the danger of breaking one or both of the electrodes, but it is also dangerous to the person adjusting the spark plug. Various mechanisms have been provided for mounting the spark plug in a fixed position and thereafter applying a force to the deformable electrode when it is desired to reduce the spacing between the electrodes. Such mechanisms have been quite complicated and expensive and also time consuming in operation.

The main object of the present invention is to provide a spark plug adjusting tool which is less expensive than similar apparatus heretofore provided and which tool may be quickly and safely employed.

Another object of the invention is the provision of two types of spark plug adjusting tools; one type for use on automotive spark plugs wherein only one deformable electrode is present and another for use on aircraft spark plugs wherein a plurality, usually four, deformable electrodes are arranged in a circular row around the central fixed electrode.

Other objects and advantages will be apparent from the following specification and from the drawings.

FIG. 1 is an enlarged fragmentary side elevation of an automotive spark plug showing one form of the spark plug adjustor mounted thereon.

FIG. 2 is a cross section of the spark plug adjustor taken in a plane indicated by lines 22 of FIG. 1.

FIG. 3 is an enlarged side elevation of an aircraft spark plug showing another form of the spark plug adjustor mounted thereon.

FIG. 4 is an end view of the structure of FIG. 3.

In detail, and with reference to FIG. 1, a typical automotive spark plug is indicated at 1 and includes a body portion 2 and a hollow extension 3 through which the fixed central electrode 4 extends. The hollow extension 3 is provided with external threads 5 which are normally employed to secure the spark plug to the engine block. Extending generally radially inwardly from the end of the extension 3 is a deformable electrode 6 so that a clearance 7 exists between the end of the central electrode 4 and the inner surface of the deformable electrode 6.

The invention comprises a mount generally designated 10 which is formed at one end to provide a cylindrical portion 11 which is internally threaded to engage the external threads 5 of the spark plug extension 3. The opposite end of the mount 10 is provided with a similar cylindrical portion 12 which is centrally threaded to receive therethrough an adjusting screw generally designated 13. As seen in FIG. 1 said screw 13 is adapted to extend through the end portion 12 and into engagement with the outer face of deformable electrode 6. Adjusting screw 13 includes a knurled head 14 to facilitate turning the same.

The ends 11, 12 of mount 10 are integrally connected together by means of a pair of relatively thin connecting pieces 15, 16 so that ample space .is provided between said connecting pieces so as to permit the insertion of a feeler gage through said spaces and into the clearance spacing 7 of the spark plug.

From this structure it will be apparent that the mount 10 is readily applied to the spark plug by means of threads 5 and the complementarily formed threads in the end portion 11 of mount 10. When it is desired to reduce the spacing 7 it is merely necessary to insert a feelder gage within said space which is a few thousandths less than the desired clearance and then turn the adjusting screw 13 until the deformable electrode 6 is in abutment with the gage. The adjusting screw may then be backed off and the feeler gage representing the exact spacing desired may be inserted between the two electrodes. It will be apparent that very little experience is required by the user to determine the exact amount of spring back of the deformable electrode 7 which takes place after the adjusting screw 13 is backed off. After the exact spacing has been arrived at, it is a simple matter to remove the tool from the spark plug 1.

FIGS. 3, 4 show another form of the invention which is adapted to be employed with an aircraft spark plug generally designated 20 and which is also provided with an extension 21 formed with external threads 22 adapted to be received in the engine block. In this form of spark plug, and as best seen in FIG. 4, there is provided a central electrode 23 which is fixed coaxial with the axis of spark plug 20. Positioned around the central electrode 23 in a circular row are four deformable electrodes 24 which are secured to the end of extension 21 in a similar manner to electrode 6 of FIG. 1. In this form of the invention a mount generally designated 25 is provided which is in the form of a hollow sleeve having internal threads adapted to be received on threads 22 of extension 21. Mount 23 is provided with four internally threaded apertures for receiving four adjusting screws 26 therethrough so that each adjusting screw may be made to register with its corresponding deformable electrode 24. With this form of the invention it is merely necessary to back off the adjusting screws 26 sufficiently to permit the mount 25 to be threadedly secured to the extension 21 as shown in FIG. 3. The adjusting screws 26 may then be turned until they are in engagement with all four of the deformable electrodes 24. A feeler gage may then be placed in the space between each electrode 24 and the central electrode 23 and the adjusting screw 26 turned until the desired spacing is achieved. By providing an adjusting screw for each deformable electrode the accuracy and speed of the adjusting operation is optimized. After the adjustment is made, the adjusting screws 26 may be backed off and the mount 25 removed from the spark plug.

I claim:

1. A tool for adjusting the spacing between the electrodes of a spark plug comprising:

a mount,

said mount being internally threaded at one end for threaded engagement with the external threads of said plug for securing said mount to said plug,

an adjusting screw threadedly secured to the opposite end of said mount for movement toward and away from one of said electrodes for deforming said one electrode toward another electrode,

said mount being formed with relatively narrow connecting pieces connecting said opposite ends to tends transversely of said central axis, said screw having its'central axis coaxial with the central axis of said plug. 

1. A tool for adjusting the spacing between the electrodes of a spark plug comprising: a mount, said mount being internally threaded at one end for threaded engagement with the external threads of said plug for securing said mount to said plug, an adjusting screw threadedly secured to the opposite end of said mount for movement toward and away from one of said electrodes for deforming said one electrode toward another electrode, said mount being formed with relatively narrow connecting pieces connecting said opposite ends to provide spaces between said pieces to permit insertion of a gage therethrough.
 2. A tool according to claim 1 wherein said other electrode is fixeDly secured and coaxial with the central axis of said plug, and wherein said one electrode extends transversely of said central axis, said screw having its central axis coaxial with the central axis of said plug. 